Can you find out the missing number in the grid?

Find a 9-digit number, which you will gradually round off starting with units, then tenth, hundred etc., until you get to the last numeral, which you do not round off. The rounding alternates (up, down, up ...). After rounding off 8 times, the final number is 500000000. The original number is commensurable by 6 and 7, all the numbers from 1 to 9 are used, and after rounding four times the sum of the not-rounded numerals equals 24.

Which fur should we be getting from the Lion?

What can you see in the middle of March and April that you can never see in any other month?

Why Aeroplane windows are round?

What number divided by 4 is the same as that number minus 4?

As a whole I am both
safe and secure.

Behead me and I become
a place of meeting.

Behead me again and I am
the partner of ready.

Restore me, and I become
the domain of beasts.

What am I?

Double it and multiply it by 4. Then divide it by 8 and you’ll have it once more. What number is it?

Two guards were guarding the camp.Guard-1 was looking towards the south to make sure no threat is coming from the road.Guard-2 was looking at the north to make sure no threat is coming from the top. Suddenly Guard-1 ask the Guard-2 why he is smiling?How Guard-1 knows that Guard-2 is smiling?

There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?